New data on the mammalian fauna from the late middle Eocene (MP 15-16) of Mazaterón (Soria, Spain): The youngest presence of the genus Prodissopsalis (Hyaenodonta, Hyaenodontidae) in Europe

Abstract

The Hyaenodonta were the most diverse carnivorous mammals in the European Eocene and were classically divided into three subfamilies: Sinopaninae, Arfianinae, and Proviverrinae, with this latter being the most successful of the three, as it exhibited a much larger geographic and temporal range. This classification is currently abandoned, as cladistic analyses of Hyaenodonta showed that several of these groups were paraphyletic. In any case, the former "proviverrines" were European endemic hyaenodontids which occupied the niche of small to medium-sized predators from the Ypresian (MP7) to the Priabonian (MP19). Recent phylogenetic proposals recognize the "Eurotherium clade" including this latter genus, besides Cartierodon and Prodissopsalis. A single species is known for Prodissopsalis, Prodissopsalis eocaenicus, previously recorded in European fossil sites of MP 12 to MP 14; nevertheless, the new material studied here, a mandible of a subadult individual from the late Middle Eocene (Bartonian, MP 15-16) site of La Solana (Mazaterón, Soria, Spain) constitutes a new species of Prodissopsalis and the youngest record of this genus up to now, extending its chronological range and remarking the shelter role of the northwestern region of the Iberian Peninsula during the Middle and Late Eocene. The new species, Prodissopsalis jimenezi provides new data not only on the eruption sequence of the genus, but also on the evolution of its dental adaptations, as the new species exhibits a more trenchant, hypercarnivorous dentition in comparison to the more primitive species P. eocaenicus, which would point toward a refining of the hunting abilities of this hyaenodont during the Middle Eocene.

Keywords: Bartonian; Eocene; Hyaenodonta; Spain; endemic faunas.

FIGURE 1

Geological map of the Duero Basin and location of the fossil vertebrate site of La Solana. (a) Location of Castilla y León autonomous community (dark gray) within Spain (light gray), showing the locations of Madrid and Soria cities. (b) Geological map of the Almazán Basin showing the location of the La Solana fossil site (modified from Ortega et al., ; Rodríguez Fernández et al., 2015).

FIGURE 2

STUS‐15077, mandible of Prodissopsalis jimenezi from La Solana: (a) right lateral view, (b) left lateral view, and (c) occlusal view. Abbreviations in Section 2.

FIGURE 3

Rendering 3D image of STUS‐15077, mandible of Prodissopsalis jimenezi from La Solana, rendered transparent to show the erupted and developing dentition in (a) right lateral view and (b) occlusal view. (c) Occlusal view of the rendered mandible to show the erupting dentition and alveoli. Abbreviations in Section 2.

FIGURE 4

STUS‐15077, right m1 of Prodissopsalis jimenezi from La Solana: (a) occlusal view, (b) buccal view, and (c) lingual view. Abbreviations in Section 2.

FIGURE 5

Comparison of the occlusal dentition in Prodissopsalis. (a) Occlusal view of GMH VI‐211‐1950, right hemimandible of P. eocaenicus from Geiseltal (MP 12–13, Germany). (b) STUS‐15077, mandible of P. jimenezi from La Solana. Abbreviations in Section 2.

FIGURE 6

Comparison of the m1 in Prodissopsalis in occlusal view. (a) STUS‐15077, right m1 of Prodissopsalis jimenezi from La Solana. (b) GMH VI‐211‐1950, right m1 of P. eocaenicus from Geiseltal (MP 12–13, Germany). Abbreviations in Section 2.

FIGURE 7

European fossil sites with Prodissopsalis eocaenicus (red dots) and Prodissopsalis jimenezi (blue dot). Columns are calibrated to International Chronostratigraphic Chart (Gradstein et al., 2012). A, age; E, epoch. Eocene European Land Mammal Ages (ELMA, see Vandenberghe et al., 2012) divided into mammal Paleogene (MP reference levels following Aguilar et al., ; Schmidt‐Kittler, 1987). PC, Polarity Chron (Geomagnetic Polarity Scale; modified from Ortega et al., 2022).